This BRSG Shared Instrumentation Grant Proposal is submitted to purchase a molecular modelling network which will be used by groups in the departments of chemistry and biology at Brown University. The hardware consists of two Silicon Graphics High Resolution Graphics Workstations, a 4D/60 and a 4D/70GT, which will be used by the chemists and biologists, respectively; two broadband Ethernet bridges to enable the workstations to communicate with each other over Brown's Brunet coaxial cable network, and to communicate with the Star 100 array processor in the computer center, and, finally, video equipment for the generation of videotapes which will record the results of modelling studies. The software to run on these molecular modelling workstations will be CHARMm (using the commercially available Quanta package from Polygen Corp.). This network will greatly assist in studies of drug-DNA interactions, in modelling the conformations and energies of new drug molecules, in modelling the dynamics of ion-ion channel interactions, in modelling the effects of substitutions on ribosomal RNA structure, in investigating the conformations of opiod and somatostatin-related peptides, in studying the possible conformations of proteins related to the mode of action of insulin, and the network will aid in research on the conformational requirements of biological electron transfer. A group of four chemists and twelve biologists make up the core of the users of this facility. In addition, Dr. Michael Pear, who is manager of academic computing services at Brown, and who has done extensive postdoctoral research in the field of molecular modelling, will serve as coordinator of the facility. At present there are no accessible high-resolution graphical facilities and no specialized molecular modelling facilities at Brown. In addition to aiding the biomedical research capabilities of the Brown faculty taking part in this proposal, these facilities that are being requested should add new capabilities to the University's research base as a whole.